Hi all,in my opinion, this correspondence should not be stored since it can be deduced straightforwardly from the principal vertices. In general, I think we should limit the data in the file without incurring a huge cost to reconstruct missing information or even risk ambiguities - both are applicable to periodic transformations; storing only principal vertices then seems the best compromise. The compacity of this section is important, since periodicity information is very difficult to partition, which means that this section should be as light as possible as it is duplicated for all partitions in case we store one file per partition - the latter option is important for very large meshes.
The ho point correspondence is stored in gmsh internal datastructures though, since it is required for ensuring continued periodicity when optimizing a high order mesh - we guarantee that the high order nodes also satisfy exactly the periodicity. In principle, adding these points should therefore not require a big effort.
This being said, there is currently an issue with reading periodic meshes : gmsh seems to displace the nodes by twice the periodicity transformation.
Best, Koen On 07/26/2018 07:34 PM, Christophe Geuzaine wrote:
On 26 Jul 2018, at 08:24, Nan Li <linan88433...@gmail.com <mailto:linan88433...@gmail.com>> wrote:Hello everyone,I am trying to mesh a cross-cavity with high order tetrahedron element (tetrahedron 10) and apply periodic boundary condition in x direction and y direction. As the periodic boundary condition has nothing to do with the cavity, you can consider the cross-cavity as a cube.I have used 'periodic surfaces' and find the mesh of the two opposite surface is identical. So far so good. Then when I look into the .msh file and try to extract the point pairs in $Periodic $EndPeriodic, I find that only the nodes on the vertex of triangle are listed there. The internal nodes for each edge are not listed.Does anyone have successfully extract the periodic pairs of internal nodes of each edge ?Indeed we only keep track of the main vertices in the Periodic section. Once you have those you can get the element correspondance and match the high-order ones.@Koen, Amaury - should we also add the high-order vertices in the correspondance tables ?ChristopheThanks. Nan LI <cross_cavity.geo>_______________________________________________ gmsh mailing list gmsh@onelab.info <mailto:gmsh@onelab.info> http://onelab.info/mailman/listinfo/gmsh— Prof. Christophe Geuzaine University of Liege, Electrical Engineering and Computer Sciencehttp://www.montefiore.ulg.ac.be/~geuzaine <http://www.montefiore.ulg.ac.be/%7Egeuzaine>Free software: http://gmsh.info | http://getdp.info | http://onelab.info
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Description: Mesh model
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